Velocity Structure of Warm Core Ring 82B and Associated Cyclonic Features

摘要

Acoustic doppler velocity measurements were made during three periods in the lifetime of Warm Core Ring 82B: April, June, and August. In April, 82B has a strong anticyclonic circulation with maximum currents of 1 m/sec. By August, the current has decreased to approximately 0.5 m/sec. Ring center determinations were made using a center of momentum method which is based on the intersections of normal lines to the velocity vectors and compared to centers obtained from a center of mass algorithm. Ring currents were decomposed into radial and azimuthal components relative to a moving ring center. In June, the maximum azimuthal current occurred at 40 km from ring center. There was not a significant radial component to the velocity. Vorticity calculations were done for a radial section of 82B revealing a core of uniform potential vorticity. A polynomial fit to the azimuthal velocity field was subtracted from the June data. The signature of the shelf-slope front and a cyclonic ringlet northeast of ring center were noted in the residuals. The remaining residual structure is attributed to ring translation. The azimuthal velocity data for the June ringlet was used with the gradient current equation and the absolute dynamic topography at 100 dbars was calculated.